Analysis of Nonlinear Ocean Wave Features in Synthetic Aperture Radar Imagery

Abstract

Spaceborne Synthetic Aperture Radar (SAR) is a reliable tool to analyze sea states in the open ocean on a global scale. The sea state information obtained from SAR systems is mainly based on two different approaches: The first approach considers the spectral description of a sea state in terms of the so-called directional wave spectrum. The second more recent approach provides estimations of the wave elevation fields in two dimensions, which permits to detect individual wave heights. Both approaches consider a linear wave field (i.e. a linear superposition of single monochromatic wave components). Although the linear wave theory is sufficient to explain most of the mean statistical features of sea states, it is no able to describe properly some wave phenomena, such as the asymmetries between wave crests and thoughts, which are of special interest for off-shore platform and ship designers. This work analyses the effects of nonlinear wave field features in the SAR imaging mechanisms in order to detect these phenomena on the SAR images of the open ocean.